I cant vote for either, as Ive had good results with both. I havent had to worry about either brand, as each provide excellent fermentation.
My previous batch was brewed with WYeast 1020 London Ale yeast and it was furiously fermenting for 2 weeks. I left this one go in the primary for the 2 weeks, and after I transfered to the secondary, it was ready to keg in a couple days.
I recently brewed my version of a West Coast IPA and used WL's brand new Pacific Ale WLP041, and its been steadily fermenting for a week and a half with a thick head of krausen which is still nice and thick.
I will continue to use both, and enjoy the spoils of both.